Uncapped quartet Caoimhin Kelleher (Liverpool), Jimmy Dunne (Hearts), Ryan Manning (Rotherham United) and Michael Obafemi (Southampton) have been named in the Republic of Ireland squad for two matches later this month.
Both Stephen Ward (knee) and Jonathan Walters (Achilles) are ruled out, but the duo of Seamus Coleman (foot) and Robbie Brady (ankle) return to the squad following injury.
Kelleher (19) previously trained with the squad in Wales following the first UEFA Nations League game in Cardiff and has travelled to Belgrade with Liverpool this week, while Dunne and Manning were recently involved in Noel King's Under-21 squad.
Dublin-born Obafemi (18) is an U-19 international, who has made two Premier League appearances so far this season.
"We have some young players coming through and over time I’m hoping that they will make the breakthrough and become proper players in the senior squad," said manager Martin O'Neill.
Midfielder Glenn Whelan will lead Ireland out as captain against Northern Ireland on Thursday week for what is expected to be his 85th, and likely final, appearance
The Aston Villa man will not be part of the squad for the Denmark game in the Nations League four days later.
O'Neill added that Everton midfielder James McCarthy had hoped to be involved but would stay with the club as he nears a full comeback from the broken leg sustained earlier this year.
Martin O'Neill says there is no update on the Declan Rice situation and he remains hopeful. He admits some circumstances favour England. #rtesoccer pic.twitter.com/rJKmQLUIbJ
— RTÉ Soccer (@RTEsoccer) November 6, 2018
Republic of Ireland squad:
Goalkeepers: Darren Randolph (Middlesbrough), Colin Doyle (Hearts), Caoimhin Kelleher (Liverpool), Sean McDermott (Kristiansund BK)
Defenders: Seamus Coleman (Everton), Cyrus Christie (Fulham), Matt Doherty (Wolverhampton Wanderers), Richard Keogh (Derby County), Shane Duffy (Brighton & Hove Albion), Ciaran Clark (Newcastle United), Kevin Long (Burnley), Jimmy Dunne (Hearts), John Egan, Enda Stevens (Sheffield United), Darragh Lenihan, Derrick Williams (Blackburn Rovers), Greg Cunningham (Cardiff City)
Midfielders: Robbie Brady, Jeff Hendrick (Burnley), Harry Arter (Cardiff City), Conor Hourihane, Glenn Whelan (Aston Villa), David Meyler (Reading), Alan Browne (Preston North End), Shaun Williams (Millwall), Richie Towell, Ryan Manning (Rotherham United), Callum O'Dowda (Bristol City), James McClean (Stoke City)
Forwards: Shane Long, Michael Obafemi (Southampton), Scott Hogan (Aston Villa), Sean Maguire, Callum Robinson (Preston North End), Aiden O'Brien (Millwall), Ronan Curtis (Portsmouth)
